Mechanism of arsenic release process from arsenopyrite chemical oxidation

Abstract

Oxidation of arsenopyrite is one of the main causes of arsenic pollution in the environment. This study, examind changes in the surface properties of arsenopyrite in the presence of oxygen. Furthermore, X-ray photoelectron spectroscopy, in situ Raman analysis, high-resolution transmission electron microscopy, and ab initio molecular dynamics were carried out on arsenopyrite, and the oxidation properties and processes of the arsenopyrite surface, along with the Fe/As/S oxidation processes, were analysed In situ-Raman spectroscopy data clearly showed that in the presence of oxygen, Fe2+ ions were transformed into Fe3+ ions on the surface of arsenopyrite at 207 cm−1, and the content of iron oxides on the surface of arsenopyrite increased significantly over time. The presence of iron promoted the oxidation of As(III), and the oxidation process was found to affect the oxidation of As atoms on the surface of arsenopyrite due to the presence of FeS bonds. The presence of As3+ intensified the oxidation of arsenopyrite surface (139 cm−1).The main reason was the presence of O2·-/HO2· on the surface of arsenopyrite, the change of Fe2+ → FeOH2+ → Fe3+ on the surface of arsenopyrite, and the change of As3+ → As4+ → As5+, which strengthened the overflow of As, leading to reconstruction and changes on the surface of arsenopyrite.